Thomas goodrum



T. GOODRUM.

Calipers. v

Patented Sept. 29, 1868.

ntrh tetra intituti Qffir.

THoMAs GooDRIUaL oF PROVIDEN'CE, RHoDnIsLAND.

Letters Patent No. 82,514, ate September 29, 1868; anteclated''eptember 16, 18 68.

IMPROVEMEN T IN GALIPERS.

TO' ALL WHOM IT MAY CONGERN:

Be it known that I, THOMAS GOODRUM, of the city and county of Providence, inv the State of Rhode Island, have invented a new. and useful Improvement in Calipers; and I do hereby deelare 'that the following'is a full, clear, and exact description of the same, reference being had to the a'nnexed drawings, making a part of this specification, in which- Figure 1 is a perspective view of my invention as attached to a pair of calipers.

i Figures 2 and 3 are detailed parts.

In the nccompanying drawings, A, fig. 2, is a short rod or round piece of metal, atone end of which is ascrew, the threads being made ratchet-shape. On the opposite end of A is fastened a suitable-shaped head, O,

to he operated by the thumb and finger. On' or near the centre of thisrod is a swell or ball, made as a bearingf in resisting end pressure. This swell or bali is fitted to a seat, as shown on fig. 3. This seat is made of Vsuitable shape or form to allow A to vibrate when in operation as a ratchet,'and also to rotate when operated'as a screjv. B, fig. 1, is a section of a circle, the under surface of which is eoncave, and provided with ratchet-teeth. cut diagonally, to fit screw on A.

- To use my invention, A being fitted into its seat,vand held there by head C, A is connected to B, so the ratchet-thread falls into and is held to the ratchet-teeth on B by a. spring. i

The advantages are the instantaneous change from one of its extreme capacities to the other, at the sameI time retaining all the qualities of nice adjustment, as, when the head, C, is pressed towards B, the ratohet-teeth are disconnected from screw on A, leaving the calipers free to open. When the pressure is removed, the ratchets again drop into their places. To close the oalipers, they are merely pressed together, A- Operating upon B as a common pawl. When required to be nicely adjusted, the head, C, is rotated, turning the screw in ratchetteeth on B, Operating the calipei'sin the desired direction. This device is applicable to dividers, Wrenches, &c.

I do not claim a pairv of calipers as my invention; but

What I do claim, and desirc to secure by Letters Patent of the United States, isp The rod A, iu connection with B, and as fitted toV its seat, substantially as described, and for the purpose as set forth.

THOMAS GOODRUM. Witnesses:

JAMES WILsoN, WM. HANcocK. 

